Respuesta :
Answer:
Since our calculated value is lower than our critical value,[tex]z_{calc}=-136.438<-1.96=z_{critical}[/tex], we have enough evidence to reject the null hypothesis at 5% of significance. So we have a significant difference between th interest rates paid by the two states.
Step-by-step explanation:
1) Data given and notation Â
[tex]\bar X_{1}=3.6[/tex] represent the mean for Georgia
[tex]\bar X_{2}=4.15[/tex] represent the mean for Ohio
[tex]s_{1}=0.03[/tex] represent the population standard deviation for Georgia
[tex]s_{2}=0.01[/tex] represent the population standard deviation for Ohio
[tex]n_{1}=60[/tex] sample size for the group Georgia
[tex]n_{2}=80[/tex] sample size for the group Ohio Â
z would represent the statistic (variable of interest)
[tex]p_v[/tex] represent the p value Â
2) Concepts and formulas to use Â
We need to conduct a hypothesis in order to check if the mean's are different, the system of hypothesis would be: Â
H0:[tex]\mu_{1} = \mu_{2}[/tex] Â
H1:[tex]\mu_{1} \neq \mu_{2}[/tex] Â
If we analyze the size for the samples both are higher than 30, so for this case is better apply a z test to compare means, and the statistic is given by: Â
[tex]z=\frac{\bar X_{1}-\bar X_{2}}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}}[/tex] (1) Â
z-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other. Â
3) Calculate the statistic Â
We have all in order to replace in formula (1) like this: Â
[tex]z=\frac{3.6-4.15}{\sqrt{\frac{0.03^2}{60}+\frac{0.01^2}{80}}}=-136.438[/tex] Â
4) Find the critical value
In order to find the critical value we need to take in count that we are conducting a two tailed test, so we are looking for thwo values on the normal standard distribution that accumulates 0.025 of the area on each tail. We can us excel or a table to find it, for example the code in Excel is:
"=NORM.INV(1-0.025,0,1)", and we got [tex]z_{critical}=\pm 1.96[/tex]
5) Statistical decision
Since our calculated value is lower than our critical value,[tex]z_{calc}=-136.438<-1.96=z_{critical}[/tex], we have enough evidence to reject the null hypothesis at 5% of significance. So we have a significant difference between th interest rates paid by the two states.